Yes, it's possible that it's been dormant that long. Is there some stress that's going along with this new relationship? By stress, I don't necessarily mean a bad sort of stress, but rather a lot of emotional energy being expended? Probably the most common trigger is emotional, often stress.
This is all speculation until you get some test results. I'm betting that it's something else anyway. I hope you'll let us know here what you find out.